On-line monitoring of pine needles combustion emissions in the presence of fire retardant using a “thermogravimetry (TG)-bridge/mass spectrometry method”

Batch and Continuous Fixed-Bed Lead Removal Using Himalayan Pine Needle Biochar: Isotherm and Kinetic Studies

Pine needle litter in Himalayan forests leads to forest fires, ground water recharge inhibition, soil acidification and contamination, and stops the growth of grass and plants. This study provides a possible solution for pine needle litter problem by converting it to biochar. Pine needle litter lying on the ground for approximately a month was collected from the Himalayan region. The pine needle litter biochars were generated using slow pyrolysis (residence time, 30 min; heating rate, 10 °C/min) at 350, 450, 550, 650, and 750 °C. Finally, pine needle litter biochar prepared at 550 °C (PNBC550) was selected for sorptive removal of aqueous lead both in batch and column studies. The PNBC550 was characterized for proximate and elemental compositions, crystallinity, surface area, morphology, and functional groups. A BET surface area of 230.9 m2/g was obtained for PNBC550. Batch sorption studies were carried out to study (1) the adsorption versus pH studies (at pH 2 to 7), (2) isotherms (at 10, 25, and 35 °C) to evaluate the temperature effect on the sorption efficiency, and (3) kinetics to reveal the effect of time, adsorbent dose, and initial concentration on the reaction rate. Increasing pyrolysis temperature raised lead sorption up to 550 °C. Lead adsorption increased considerably as pH rose from 2 to a maximum adsorption around pH 5 and above. The sorption data were fitted using different isotherm models and kinetic equations. The Langmuir adsorption capacity increased from 22.93 mg/g at 10 °C to 40.43 mg/g at 35 °C, showing that adsorption was endothermic. Fixed-bed studies were conducted at room temperature with an initial lead concentration of 7.85 mg/L and 4.0 g of PNBC550 at initial pH 5.0 and a flow rate of 3 mL/min. Desorption studies conducted under the same experimental conditions found about 90-93% lead recovery. Development of high-efficiency biochars for lead remediation provides a sustainable solution for the Himalayan pine needle litter problem. The biochars also possess the possible potential for aqueous removal of other metal cations.

Evidence of enhanced atmospheric ammoniacal nitrogen in Hells Canyon national recreation area: implications for natural and cultural resources

Agriculture releases copious fertilizing pollutants to air sheds and waterways of the northwestern United States. To evaluate threats to natural resources and historic rock paintings in remote Hells Canyon, Oregon and Idaho, deposition of ammonia (NH3), nitrogen oxides (NOx), sulfur dioxide (SO2), and hydrogen sulfide (H2S) at five stations along 60 km of the Snake River valley floor were passively sampled from July 2002 through June 2003, and ozone data and particulate chemistry were obtained from the Interagency Monitoring of Protected Visual Environments (IMPROVE) station at Hells Canyon. NH3 concentrations were high; biweekly averages peaked at 5-19 ppb in spring and summer and the nutrient-laden Snake River is a likely source. Fine particulate ammonium nitrate (NH4NO3) averaged 2.6 microg/m3 during the 20% of worst visibility days with winter drainage of air masses from the Snake River Basin and possibly long distance transport from southern California. Other pollutants were within background ranges. NH3 is corrosive to clay-based pictographs; nitrogen deposition can alter natural biotic communities and terrestrial ecosystem processes at levels reported here.